1. Field of the Invention
The present invention relates to superconductive electromagnets, and more particularly to a cooling apparatus for a superconductive electromagnet apparatus configured to operate as a superconductive magnet at a cryogenic state.
2. Description of the Related Art
In general, a superconductive electromagnet apparatus is configured to receive an applied electrical current and to generate a strong magnetic field by operating as a superconductive magnet at a cryogenic state.
The superconductive electromagnet apparatus as such includes a coil configured to generate a magnetic field when an electrical current is applied and to operate as a superconductive magnet in a cryogenic state, a housing having a shape of a ring in which the coil is positioned, a helium container in which a coil assembly is positioned and in which helium in a liquid state is retained, and a cryogenic cooling apparatus configured to cool off the helium such that the helium maintains the liquid state.
Thus, when heat is generated from the coil, the helium in a liquid state, which fills an inside of the housing, changes into a gaseous state by absorbing the heat, and the helium in the gaseous state, having a relatively lower density compared to the helium in a liquid state, moves to an upper side of the housing due to the difference of density. The helium in the gaseous state, which moves to the upper side of the housing, is cooled off by the cryogenic cooling apparatus that is disposed at an upper side of an inside of the housing, and so the helium changes again into the liquid state, and thus the coil disposed at an inside of the housing may continuously maintain the cryogenic state.
When using the superconductive electromagnet apparatus, a magnetic resonance imaging apparatus is configured to obtain a cross-sectional image of a body by using a nuclear magnetic resonance phenomenon that occurs due to a strong magnetic field generated from the superconductive electromagnet apparatus, and is referred to as Magnetic Resonance Imaging (MRI).